Judging by the video the voice actors are certainly not "a bunch of nerds". I've heard plenty amateur voice acting in various mods and indie games over the years and the stuff that's on display in that video is all surprisingly well acted (and written). Given, that there's 50 different voice actors involved, i doubt the overall quality of the mod is continuously that good, but the stuff here easily rivals even Bethesdas official voice actors. I'd say they are probably at least experienced amateur theatre actors or somesuch. And whoever coordinated the mod, knows their sound stuff. Sound quality stays good throughout and all the actors used at least half decent equipment.
Conclusion: I'll certainly follow (and eventually use) that mod.